Automatic control of tuning and band width



Aug. 17, 1943.. H. VBOUCKE 2,327,244

AUTOMATIC CONTROL OF TUNING MED BAND-WIDTH F i1ed Ma 24, 1941 2 Sfieets-Sheetl 3 M, 4 5 M2 M3 /6 g I 1m 10 7 9 a 11' )2 I9 I7 18 MOTOR a? T; PLATE C lRC U/ 7' M6 0F (ONT/POL TUBE INVENTOR ATTORNEY H. BOUCKE Aug. 17, 1943.

AUTOMATIC CONTROL OF TUNING AND BAND-WIDTH Filed May 24. 1 941 2 sheets sheet 2 INVENTOR HEM/Z B0 C/(E BY #5 I 2 I ATTORNEY A vvvl.

Patented 'r ruga 1% i943 giant nn romarro ooN'rnot or" re 113mm rn Heinz Bourke, Berlin, Germany; vested in the vAlien Property Custodian Application May 24, 1941, Serial No. 294,99

Germany March 2, 1940 'z Elahns. (c1. est-2c) It is known to tune a receiver by means of a 7 motor in the vicinity of the receiver, or from a remoteplace, whereby the motor is switched in for instance by means of push buttons assigned automatically coupled from the tuning arrangement to the band width control device by means of a relay which has come to rest by the interrupted motor current so that the elements of the band width control are gradually moved in the sense of a decrease, or increase of the band width until the band width is reached which is tion for the second measure.

' .that they can be axially 'moved, whereby the obtained through mechanical means'by setting a contact disc by means of the band width'control potential, as well as with the aid of a time constant organ charged by thecontrol potential.

The Figures 1 and 2 show an example for the first measure and the Figure 3 shows a construc- The arrangement according to Figure 1 operates as follows: The shaft 3' of the motor 2 which issfed from the current source i has three bevel gears (7, 8 and it) so mounted thereon bevel gears l, or 8 which are connected with each other serve for the clockwise turning or counter clockwise turning of the tuning means 35. This coupling is effected by the magnet coils M1, or

M2 which are adapted to pull inwards against the pressure of the springs ill, or' H the magnetic hollow shaft isupporting the bevel gears l and 8. The rotational force of the shaft 3 is transmitted-to the hollow shaft-across a pin determined by the power of. the desired transmitter and/or nearby transmitter .with the view to reducing the receiving power of nearby trans mitters. r

In case of a remote operation of the receiver it is already known first to employ the tuning motor for the tuning and then for setting the volume, but the re-coupling and switching of the motor to the secondhand was done by a switch to be operated at/wilh In contrast therewith in the present invention the difference is that firstly the tuning motor instead of adjusting the volume; carries out a control of the band width and secondly instead of this performancebeing carried out by a manual controlit is done in a fully automatic fashion after the tuning is completed.

The idea of the present invention is put into practice in that the time period during which the motor actsvmechanically upon the control elements of the band width moving them from one limit value in the sense of an increase, or

decrease, is determined by the value of the receiving field strength-0f the transmitter tuned to, i. e. in dependence on the volume control potential or in dependence on the ratio between the field strength of the desired transmitter and that of the neighboring transmitter, or onboth which engages in the slot 5 of said hollow shaft. Whether the 'bevel gear 1 or 8 is coupled with the bevel gear 9 and thus with the tuning means 3| depends on the position which the drum 35 has with respect to the key, orgroups of keys 44 having been depressed for the purpose of tuning. The surface of the drum is divided into two conducting surface parts in a manner known as such and which are electrically separated by an insulating strip 3T extending obliquely to the shaft, wherebythe one surface part is connected to an end of the coil M1 while the other part is conductively connected to an end of the coil; M2. In the position of the switch herein shown, the contact next to the bottom contact is depressed whereby the magnet coil M2 is switchedin which forces the bevel gear 1 against the bevel gear 9 thus turning the drumuntil the depressed con tact on reaching theinsulating strip interrupts the circuit. This circuit extends from the motor 2 along the line 39. across M1, or M; to the-drum 36 from there through the contact group 44, across the line 35', to a. further magnet cofl M4 whose purpo'se'will be described below,'and from there across the line 34 to a. further magnet coil Me which pertains to 'a relay. From there the current returns to the current source'l through the lines 33 and 32.

values. In the last-mentioned cases the intensity of the 9 kilocycle local oscillation whistling can' be considered as a measure for the said time period. The control of the time of action of the motor on the control of the band width can be After the tuning is completed among other thing's also the relay coil M5 which falls ofi with delay has no longer current. Thus the. line 43 will be connected with the line 52 and the motor will be switched in again. However, since the i I coils M1 and M2 receive no current while the bevel gear 9 takes up the position in the center between the bevel gears l and 8, the tuning will in no ways be affected. Now the current passes from the'motor across the lines 39 and it to the magnet coil M3 which draws in the armature joined with the bevel gear iii, thus coupling the bevel gearifi with a larger. bevel gear ill which the band width. The armature 36 has a cord- 29 fastened thereto which is several times wound about the shaft 28 of the said disc 2'5 and which is tensioned by a spring iii. The disc 2i carries on. its" circumference conductive ring which is interrupted by a grooved place C 6 (Fig ure 2) of insulating material. The position of wise sense (Figure 2) and the inore so the furtherthe groove 38 has moved likewise in the clockwise direction. Thus the band width will reduce its width the more, the weaker the station tuned to. If the contact arrives in the notch, the circuit will be interrupted and the elements of the band width control remain in the assumed position. On account oi. the arrested'contact also the disc 2'17 remains in position despite eventual variations in the control performance.

Now if by depressing another push button another station is tuned to, then by means of the relay. M5 also at this place the circuit effective for the control of the band width will be interrupted and at the same time the attracted armasaid grooved place dd shown in Figure 2 is assurned at receiving a local station where the current passing through the coil Mu has a minimum value. "When tuning to ,a more distant station, the current increases, the armature 3Q will be attracted and, the disc 21 turns in the direction of tie arrow shown in Figure 2. The grooved place G6 assumes herebyfor instance the position Lil, or the position (16" in case of a still weaker station. This signifies that the circuit is closed by means of the co t? ct gliderflt and that therefore the gear ll wi e driven. Consequently, the cord 2@ tensioncd by a spring i i and wound around a wheel 20 will be unwound, thereby turning the wheel 26 and at the same time the device for controlling the hand width. 1 This wheel 2i is coupled through the shaft 25 with the disc 22 on which the contact is conductively mounted. Furthermore, a magnet armature 26 is mounted on the shaft and which can be drawn into the magnet coil M4. As long as Mr is without current, i. e. during the control of the hand width and thereafter, the

spring i8 forces itself against the armature 2G and tl'ierehy a ainst the shaft 26 with the 'efiect that the disc 22 is pressed against the fixed di c 28. By providing sufficient roughness of the surfaces'of 22 and 26 which face each other (for instance rubber layer) the brake .force is increased to such an extent that on the one hand.

it will not be overcome by the downward pu l of the spring iii which ismore or .less tensioned in the course of the control, and that on the other hand, a turning of the disc by means of the motor 0 in the opposite direction will he possible. I

The pulled, or rotary parts oiithe elements for the control of the band width are connected with the wheel 2i, or with the disc 22, or with the part of the cord Zii residing between the spring M and .the/ wheel M. For instance, a

, takes place.

- the elements for the hand wi l1 ture 22G of the magnet li i'r removes somewhat the disc 22 including the contact "3 from the disc 24 so that the spring EC can set the elements of the band width control into the initial position, i. e. to maximum band width the present example of construction. Obviously, through a slight modification 01' the arrangement the latter can he so adapted that the narrowest hand width serves as initial position (in the example of construction described at the end of the de scription.this bringing hacl; into the initial position is not required).

In the present example it is not advisable to insert a friction coupling between the gear ill and its shaft in order to avoid that the cord will eventually be tensioned too much.

The arrangement according to Flame 3 is to a large extent identical with the arrangement shown in Figure l. However, the arrangement is shown at the moment in which the tuning is completed and the control of the hand width As in the case of Figure l, the motor circuit for accomplishing the tuning is closed across themagnet coil Id; and relay M5. In the arrangement the shaft 26 has no longer the disc 22 and ccntactbar 2Q and furthermore the device shown separately in re 2 is no longer present. Just as in the c of Figure 1, control driven by the wheel 2i, cord drive 20 and linl; W.

As regards the tuning circuit there exists in the circuit of Figure 3 as compared with that of Figure l the sole difierence that the relay coil M5 instead of pertainingto a switch-oil.

relayfbelcngs to a reversing relay. There is pulling rod R connected with the coupling coils of the band filters F and actuating thelatter, can be so connected with the'linlz Gil that the further the said link moves in the directihn (N) towards the wheel ill, the narrower becomes the band width. Movement of the link 4171 and rod R in the direction W provides adiustment of 9.

turns and therewith thecontact 28 in the clock- 'wider band-width. Meantime also the disc 22 effective circuit for the hand width control. On reaching the proper. tuning position the release of the armature from the relay Mu eiiects the closing of the circuit for the hand width control across the lines 69, it? and (ii and across the contact of the relay M6 at the right hcttom of the figure. The magnet ll h e ects in the manner already described, the coupling of the bevel gear it) with the bevel gear ll.

The time during which the motor acts upon the elements of the hand width control is deterruined by the duration of the discharge of the condenser ill across the resistor [56, namely as follows: Thetuhe Eii represents a controlled high frequency tube, or intermediate frequency tube oi the receiver whose grid circuit has at arrow 52 the volume control potential applied thereto in; the customary manner. The end of the oathode resistance of this tube which faces awayfrom the cathode is placed at ground, or at the mass.

Between this point and the minus pole of the line section designated by [it a resistance 55 is inserted which is passed by the cathode current of resistance is bridged as regards high frequency and audio-frequency,

The direct potential appearing at the resistance 55 is higher, the lower the field strength of the station tuned to. Since in the state oi rest of the drive device, that is during the tuning operation, this potential has its negative pole placed at the grid of the auxiliary tube 54 across the lines d, the'said tube is blocked and no current passes through the relay Me. .Now, through the release of the armature of the relay M5 at the start of the control of the band width, the lines there separated, the condenser 5? will be dis,- oharged across the high-ohmic resistance 5t and a strong plate current begins to flow in the auxilary tube as after a certain time period which depends on the value of the initial potential at the condenser at as well as on the dimensions of the condenser 51! and of the resistance 56 whereby said current terminates, by means of the relay Mathrough the falling-oil of the relay M5, the

setting operation of the band width in the position shown. In this circuit the plate potential and therewith the value of the plate current which flows during the unblocked state oithe auxiliary tube lit will he set by the resistances 5d and The following dimensions for the memher are given by way of example: Condenser 5']=1,uf., resistance 56:3 megohm.

Moreover sufficient time must be available in order that on reaching the correct tuning position the condenser W can charge itself across the lines-5t to the potential'value corresponding with the received. station. Thus, when the proper tuning position is reached the relay M5 shall not open the circuit to instantaneously, but instead with a certain delay such as for instance 0.3 to 0.5 sec.

In the case of motor tuning it is customary to disconnect in some way parts of the receiver so as to render inaudible the freqeuncies existing between the station last tuned to and the station being tuned to. 'illso in the case of the control device according to the present invention the same measure will preferably be resorted to and the reproducing organ switched-in after the'tuning is completed. It .will' however, be/unnecessary to wait with the switching-in of the reproducing apparatus until the control of the band width is completed, because this control does not disturb the reception. V

The present invention aflords the control of the band width in all high frequency and intermediate frequency stages since through the motor a suificient driving power and setting power isavailable.

What is claimed: y i

1. In a. radioreceiver provided with tuning means and means for controlling the band-width of the received signal, automatic control means including a motor for adjusting thetuning means to a plurality" of predetermined stations, and

sesame i dependence upon the signal strength of the tuned-in predetermined station.

2-. In a radio receiver provided with tuning means and means for controlling the band-width of the received signal, automatic control means for adjusting the tuning means to a plurality of predetermined stations, means operated upon cessation of the tuning means for initiating the adjustment of the band-width control means,

and means operative in dependence upon the signal strength of the tuned-in predetermined station for completing the adjustment of the band-width control means.

3. In a radiovreceiver provided with tuning means and means for controlling the band-Width.

of the received signal, automatic control means for adjusting the tuning means to a plurality of predetermined stations, means operated upon cessation of the tuning meansfor initiating the adjustment of the band-width control means, a

control circuit including a condenser which during the tuning operation is permitted to be charged to a value in dependence upon the 'signal strength of the tuned-inpredetermined station, and means operative bydischarge of said condenser after cessation of the tuning'operation for completing the adjustment of the band-width control means.

4-. In a radio receiver, means for automatically adjusting both the tuning and the selectivity or bandwidth of the receiver in response to the selective actuation of one of a plurality of pushbuttons corresponding to predetermined stations, said means comprising a motor, means interposed between the motor and the tuning means for driving the latter in either of two directions depending upon the actuated push-button, a relay included in the motor circuit whichupon deenerr gization with adjustment of the tuning means causes closure of an alternative motor circuit for actuating the band-width control, and means responsive to the signal strength of the tuned-in predetermined station for determining theadadjusting both the tuning and the selectivity or band-width of the receiver in response to the selective actuation of one of a plurality of push ,buttons corresponding to predetermined stations,

saidi means comprising a motor, means interposed between the motor and the tuning means for driving the latter in either of two directions depending upon the actuated push-button, a relay. included in the motor circuit. which upon deenergization with adjustment ofthe tuni means causes closure of an alternative motor circuit for initiating the adjustment of the bandwidth control, and means operative in dependence upon the signal strength of the tuned-in predetennined-stationsfor breaking said alternative motor circuit-and simultaneously completing the adjustment of the band-Width control. 6. In a radio receiver, means for automaticall adjusting both the tuning and the selectivity or band width of thereceiver in response to the selective actuation of one of aplurality of push .buttons corresponding to predetermined stations, said m'eanscomprising a motor, means interposed between the motor and the tuning means for driving the latter in either-of two directions means under control of said motor and operated depending upon the actuated push-button, a re-- lay included in the motor circuit whichupon deenergizatioh with adjustment of; the tuning means causes closure of an alternative motor cirtermmed station, and means eperatiVe-by, dlscharge 01 said condenser eiter cessation of the tuning operation fer breaking said alternative motor circuitencl sflmulteneeuely' completing the adjustment oi the bend-=Mdth eentrefi.

7. In a, radio neeeiver'of the type privlded with e tuning meens and e bend-width adjusting means, control mechanism, we automatically ed plating the adjustment, of the bend-Width eonjusting both the tuning means and the benc'imam adjusting means, eemmlelne e metal, e two-pare commutator emxee ice the tuning means eeeaeee end delved 2037 the meter, e plurality oi selective- ;ly operable key contents cooperating with the commutator fee determining the direction 02- I0- tetion end the adjustment of the tuning means,

e relay included in the motor circuit which upan deenergizetien with adjustment of the tuning" means causes closure of en eltemeeive motor circult for initfleting the edjustment of the bandwidth control, end means operetive in dependmade upon the signal strength of the tuned-in predetermined stations for breaking said alternative motor circuit and simultaneously comtrol. 1

EEINZ 30mm. 

